Flash Flood Guidance
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Issued by NWS
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027 AWUS01 KWNH 241739 FFGMPD NMZ000-AZZ000-UTZ000-NVZ000-242337- Mesoscale Precipitation Discussion 0494 NWS Weather Prediction Center College Park MD 138 PM EDT Mon Jun 24 2024 Areas affected...Southwest U.S. Concerning...Heavy rainfall...Flash flooding possible Valid 241737Z - 242337Z SUMMARY...Scattered showers and thunderstorms will be capable of producing high rainfall rates again today, which may result in a few areas of localized and small scale flash flooding. DISCUSSION...Recent visible satellite imagery indicates convection is beginning to develop across the higher terrain of central AZ into western NM. Compared to yesterday, CAPE and PW values are equal or even a bit higher in spots today across this region. The convective QPF signal in the HREF is also slightly higher today, especially across central AZ into west central NM. HREF EAS probabilities of exceeding 0.25" in 6 hrs were only 5-10% yesterday, but are ~15-40% today. These higher EAS probabilities are indicative of greater convective coverage in the HREF today compared to yesterday. Observational trends noted above tend to support this outcome as well. There were a few flood advisories and flash flood warnings that resulted from convection yesterday, and given the similar to slightly better environment today, would expect a similar outcome. As convective coverage and intensity increases with daytime heating a localized flash flood risk should evolve. Like the past couple days, slot canyons, burn scar areas and the normally dry washes will be most susceptible to isolated flash flooding. There is more cloud cover over southeast AZ today which may delay convective initiation there. However the remnant MCV that is visible on satellite imagery over this area should eventually help aid in convective development. The threat is more conditional over south central AZ. The best overlap in instability and PWs are forecast here, but the trigger for convective development is a question. However if any cells do form they will be capable of intense rainfall rates. And while probably after the valid time of this MPD, there is some signal that convection may eventually organize along the terrain of central AZ and push south towards the Phoenix to Tuscon corridor tonight. This could eventually push an isolated flash flood risk into these areas, and so will continue to monitor trends. Chenard ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...PSR...SLC...TWC...VEF... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 38681158 38451131 37981135 37171193 36341193 35261092 34950947 35240874 35260793 34970702 34600601 34290543 33710514 33040532 32690572 32940617 33210644 33440675 33330737 33130814 32750870 32050918 31550926 31200972 31261044 31241104 31381162 31781233 32241270 32861264 33711283 34311332 34491363 34851413 35841424 37001415 37731405 38001341 38121303 38141260 38491202